1. Field of the Invention
The present invention relates to a webbing tension device which imparts tension to an occupant restraining webbing during a vehicle emergency situation to restrain an occupant.
2. Description of the Prior Art
A seatbelt system for protecting the occupant in an emergency situation is constructed so that the webbing, one end portion thereof being retracted in layers into a webbing retractor, is fastened about the occupant and the occupant is restrained by the webbing during the emergency situation.
The webbing retracts retracting the webbing therein imparting a predetermined tension to the webbing. However, a retracting force of the webbing retractor is made relatively weak or it is completely removed, thereby forming a clearance between the occupant and the webbing fastened about the occupant so as not to press the occupant.
Accordingly, a tension device transmitting a biasing force of such resilient means as a coil spring to a webbing takeup shaft of the webbing retractor to impart a tension to the webbing in the emergency situation of the vehicle has been proposed in the conventional arts. In the tension device a pawl in the webbing retractor is latched to a wheel rotated together with the takeup shaft and receiving the biasing force and the pawl is separated from the wheel by a magnetic force of a solenoid in the emergency situation of the vehicle, whereby the biasing force received by the wheel is transmitted to the takeup shaft.
In the conventional tension device, also, the wheel is provided at its outer periphery with a cutout, a latching portion thereof being formed in a radial direction of the wheel, and a rotating force of the wheel due to the coil spring acts upon the pawl so as to press the pawl in a direction of a support member supporting the pawl, whereby the latching situation between the wheel and the pawl is maintained. Accordingly, a large force is required to release the pawl from the wheel in the emergency situation of the vehicle and, if the force acting upon the pawl is made weak, then there is such a fear that the latching situation between the pawl and the wheel is released due to vibrations or the like occurring in an ordinary running situation of the vehicle or at times of opening and closing of the doors of the vehicle.